2.2 External cost assessment of the European incineration directive

Under a directive of 1989, limits were placed on the atmospheric emissions from municipal waste incinerators operating within the EU (European Commission, 1989). In 1994 a draft directive was published which suggested, among other measures, tightening the emission limits. A selection of the 1989 limits and 1994 proposals are summarised in Table 7. Limits were also set for heavy metals but the combination of metals was different in the two directives.

The UK’s Energy Technology Support Unit was asked by the European Commission to assess the costs and benefits of the proposed changes (Brown, 1996). Determining the private costs of the measure is beyond the scope of this course, but quantifying the externalities provides an interesting example of the use of this tool.

The assessment was based on the ExternE methodology, which can be summarised as:

• determining the emissions
• using dispersion modelling tools to determine the exposure to potential receptors
• evaluating the uptake pathways by receptors (for human exposure)
• using the dose–response function to assess the damage caused
• valuing the damage caused.

The emissions were calculated for a range of incinerator sizes fitted with several pollutant abatement systems. All the systems met the requirements of the directive, but the spread of technologies allowed comparisons between the systems common in different countries.

The dispersion modelling used standard atmospheric dispersion models that took account of both local (less than 50 km from the source) and long-range (more than 50 km from the source) receptors. As explained by Friedrich et al. (2001) the longer-range dispersion allowed the formation of secondary pollutants such as sulfate and nitrate aerosols and ozone to be covered.

The number of receptors affected by the pollutants depends on the height of the discharge and the number of people in the area. This was taken into account by considering three discharge heights (50 m, 90 m and 100 m) and three specific areas within the EU (Paris, Stuttgart and Birmingham).

When modelling the uptake, the ExternE approach was adopted of assuming that for macro-pollutants, such as sulfur dioxide (SO₂) and oxides of nitrogen (NOx), exposure is all due to inhalation. For micro-pollutants such as heavy metals and dioxins, multiple pathways must be taken into account. These pathways are summarised in Figure 1.1. In both cases, ExternE models were used to estimate the uptake of most substances and models from the US Environmental Protection Agency (USEPA) and the World Health Organization (WHO) were used for dioxins and mercury.

Maximise

Figure 1 Micro-pollutant uptake pathways

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Figure 1 shows a flow diagram which begins ‘plant emissions’ from a power plant that flow to two boxes via an arrow labelled ‘air dispersion’.

The 2 boxes are labelled, ‘wet and dry deposition’, and ‘air concentration’.

From air concentration, there are 3 arrows, one that is labelled ‘inhalation’ and leads to the end of the diagram, to a box labelled ‘receptor – mother’s milk, ingestion’; one that is labelled ‘diffusion’ and is pointed to a depiction of a field; and one arrow is leads to a box labelled ‘water concentration’. From ‘water concentration’, there are two arrows, one labelled ‘water consumption’ and leading to end of the diagram, and the other labelled ‘bioconcentration’ and leading to a box labelled ‘fish concentration’. From there is an arrow labelled ‘fish consumption’ and leading to the end of the diagram.

Back to the box labelled ‘wet and dry deposition, there are two arrows, one leading to ‘water concentration’, from where it follows the same path as previously described from there, and one arrow labelled ‘deposition’ that leads to a box labelled ‘plant concentration’. From this box there are 3 arrows leading from it and one to it:

• The arrow leading to it is labelled ‘root uptake’ and is from a box labelled ‘soil concentration’.
• The first arrow leading from it is labelled ‘plant consumption’ and leads to a box labelled ‘animal concentration’, which then leads to the end of the diagram via an arrow labelled ‘meat and dairy consumption’.
• The other two arrows leading from it lead to the end of the diagram, one is labelled ‘above ground vegetable ingestion’, and the other ‘below ground vegetable ingestion’.

Back to the box labelled ‘soil concentration’, there are three other arrows from it as well as the one previously described to ‘plant concentration’:

• The first arrow is labelled ‘erosion, leaching and runoff’ and leads to ‘water concentration’, from where the flow chart follows the same path as previously described from there.
• The second arrow is labelled ‘soil ingestion’ and leads to the end of the diagram.
• The third arrow leads to ‘animal concentration’, and follows the same path as previously described from there.

Figure 1 Micro-pollutant uptake pathways

Once the doses were established, the ExternE methodology was used to determine the damage caused.

Valuation of the impacts was based on willingness to pay. In the case of mortality, it is important to stress that the sum does not represent the value of a life, which is priceless, but people’s willingness to pay for a reduction in the risk of death. This willingness is based on research using opinion surveys and monitoring expenditure on items such as nicotine patches among smokers and purchase of cars with airbags (when airbags were an optional extra rather than a standard fitting).

Results

The results in terms of damage cost per tonne of each pollutant emitted are shown in Table 8 for Stuttgart and a 90 m discharge height; the values for Paris are higher and those for Birmingham are lower due to differences in the exposed populations. Not surprisingly dioxins and heavy metals result in the highest damage costs and health impacts are far more important than building damage.

Table 8 Damage cost per tonne emitted

Pollutant	Impact	Damage cost (€ per tonne)
Dioxins	health	2.43 × 109
Cadmium	health	1.04 × 106
Arsenic	health	1.27 × 106
Chromium	health	1.05 × 106
Nickel	health	2.14 × 104
Particulate matter	health	147 500
Oxides of nitrogen	health	63 248
Sulfur dioxide	health	27 494
Ozone	health and crops	5 060
Sulfur dioxide	buildings	614
Oxides of nitrogen	buildings	307

Source: Brown (1996, pp. 5–17)

Burning a tonne of waste releases different quantities of each pollutant so a more useful value is the damage caused per tonne of waste burned and this is shown in Figure 2. The range of values represents the different pollution abatement systems considered.

Adapted from Brown, 1996, pp. 5–18

Figure 2 Range of damage costs (€ per tonne burned)

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Figure 2 shows a bar chart.

The y-axis is labelled ‘damage cost (€/tonne burned)’ and numbered from 0 to 40, in increments of 5.

The x-axis has 6 labels, which are:

• Particulate matter
• SO₂
• NO_x
• Organic carbon
• Metals
• Dioxins

The legend consists of 2 labels:

• Maximum (in the colour green)
• Minimum (in the colour purple)

For ‘particulate matter’, the maximum damage cost is approx. 2.5 €/tonne burned. The minimum impact is approx 1 €/tonne burned.

For ‘SO₂’, the maximum damage cost is approx. just over 5. The minimum impact is approx 1.5.

For ‘NO_x’, the maximum damage cost is approx. 38. The minimum impact is approx 17.

For ‘organic carbon’, no maximum or minimum damage cost is shown.

For ‘metals’, the maximum damage cost is approx. 0.5. No minimum impact is shown.

For ‘dioxins’, no maximum or minimum damage cost is shown.

Figure 2 Range of damage costs (€ per tonne burned)

Figure 2 demonstrates the, possibly counter-intuitive, result that oxides of nitrogen are by far the most significant pollutant and that dioxins, although they have a much higher profile, have no detectable damage costs.